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Place · Level 3
一碳单位搬运工 · DNA 合成的材料流 · 和 B12 共管甲基化
synergy · 3
Choline supplies the BHMT remethylation backup to MTR (B12/folate). Low folate raises choline demand.
↔Iron
Both are required inputs to red-cell production, but their deficiencies pull opposite ways: iron shortage makes cells small, folate/B12 shortage stalls DNA synthesis and makes them large. Lack both and MCV lands back in the 'normal' band, hiding both problems at once.
There are two routes back from homocysteine to methionine: one runs on folate and B12, the other has TMG (betaine) hand over a methyl directly. Under methylation strain they run in parallel — neither replaces the other.
cofactor · 4
B12 + folate run the methylation cycle together. Folate alone masks B12 deficiency anemia.
PLP runs SHMT (serine ↔ glycine + 5,10-methylene-THF) and Hcy transsulfuration. Folate and B6 occupy two sides of the same junction.
The neural tube closes 21-28 days after conception — before most people know they are pregnant. Proliferation peaks then and runs on folate-driven one-carbon metabolism for purines and thymidine, which is why the supplementation window is preconception.
Glycine cleavage + SHMT funnel Gly one-carbon units into 5,10-methylene-THF; nearly half the one-carbon pool comes from Gly.
antagonism · 1
↮Zinc
Folic acid + Zn form insoluble complexes in gut → mild Zn absorption decrease at supplement doses. Clinically weak but informs prenatal multivitamin co-dosing design.
depletes · 1
Chronic alcohol depletes folate via 3 pathways: (1) inhibits intestinal γ-glutamyl hydrolase → ↓absorption; (2) accelerates renal excretion; (3) disrupts hepatic one-carbon metabolism. Alcohol + low folate → ↑homocysteine + aberrant DNA methylation → accelerated alcoholic liver injury. Pregnancy drinking is especially dangerous (NTD risk stacking).
regulates · 1
Folate and B12 deficiency need checking together on the fatigue line: their haematology looks alike, and folate alone masks the anaemia of B12 deficiency while neurological damage carries on behind a normal blood count.